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Unnecessary start points ruining print, please help


LazZer
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Posted · Unnecessary start points ruining print, please help

Hey folks. I've been trying to print some items that end with a few layers of single lines. However, Cura's been doing something weird that I can't understand which is ruining my prints. I've attached a picture of the sliced print. The printhead goes around the layer (starting from the yellow circled start point and going left from this perspective), prints the whole layer flawlessly, and then for some reason hops to the "start point" marked with green and then the one marked with blue. Apparently it does nothing at those points (especially considering they are completed lines), but because of the hops, it leaves a gap at the start of the next layer, and does that layer after layer. So is there any way I could erase those unnecessary start points, or does anyone have any idea how I could make this print come out as it should? I've tried reducing the retraction distance in hopes of fixing it, and I think I maybe could push it even lower, but I'd rather fix the issue itself than go with a workaround that would reduce print quality as a whole.

curaissue.jpg

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    Posted · Unnecessary start points ruining print, please help

    Without the model I'm guessing.  When points come together like an arrowhead they are wider (at their base) than the line width.  Do you have "Fill gaps between walls" set to Everywhere?  Because it sounds like it's doing what it's told.  With the setting at "Nowhere" it won't go back to fill those little gaps.

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    Posted · Unnecessary start points ruining print, please help

    It looks like a cookie cutter and cookie cutters are tough.  If you have combing turned on then there is so much travel movement that the nozzle pressure falls off beyond what a retraction alone does.  That causes the prime to be insufficient to make up the difference.  There is a post processing plugin called Retract Continue that can help.  It doesn't work if there are Z-hops in the file.  I haven't used it - I just know it's there.

    The beta for Cura 5.0 is out and it's called Arachne.  It features variable line width and using Arachne might fix the problems you are having. 

     

    You can find a link to the download by searching either HERE or on Github.  You do not have to uninstall your current Cura version.  It's much better at thin walled models.

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    Posted · Unnecessary start points ruining print, please help
    19 minutes ago, GregValiant said:

    It looks like a cookie cutter and cookie cutters are tough.  If you have combing turned on then there is so much travel movement that the nozzle pressure falls off beyond what a retraction alone does.  That causes the prime to be insufficient to make up the difference.  There is a post processing plugin called Retract Continue that can help.  It doesn't work if there are Z-hops in the file.  I haven't used it - I just know it's there.

    The beta for Cura 5.0 is out and it's called Arachne.  It features variable line width and using Arachne might fix the problems you are having. 

     

    You can find a link to the download by searching either HERE or on Github.  You do not have to uninstall your current Cura version.  It's much better at thin walled models.

     

    I've been researching things, and it seems like boosting the number of triangles in the model in Fusion 360 fixes matters more or less, but I wonder if boosting Retraction Extra Prime Amount could maybe compensate for the nozzle pressure drop? Also, how stable and reliable is 5.0 beta? I might just migrate if it doesn't require too much tinkering under the hood. Thanks for your help so far regardless!

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    Posted · Unnecessary start points ruining print, please help

    It's stable as far as just being able to run and I haven't come across any issues with it at all (I run Windows).  I don't do things that are "mission critical" though so I tend to use the beta versions when they come out and see if there are any problems the Cura team is unaware of.  It's part of my payback for the excellent help I got here when I was starting out.

     

    As I say, there is no need to uninstall your old version as Arachne is a stand-alone installation.  If you are prompted just say no.

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